1. Field of the Invention
The invention relates in general to systems for displaying images including liquid crystal display modules and in particular to liquid crystal display modules preventing incursion of dust.
2. Description of the Related Art
Referring to FIG. 1, a conventional touch panel type liquid crystal display module primarily comprises a plastic frame 10, a bezel 20, a rear shield 30, a touch panel 40, a flexible sealant R, a display unit 50 and a backlight unit 60, wherein the plastic frame 10 surrounds the display unit 50 and the backlight unit 60. As shown in FIG. 1, the plastic frame 10, the display unit 50 and the backlight unit 60 are encompassed by the bezel 20 and the rear shield 30. The touch panel 40 is adhered to the bezel 20 and positioned over the display unit 50. The touch panel 40 is an user interface, allowing the user to interface with the display module and/or the computing device operatively coupled thereto, by simply touching the touch sensitive surface of the touch panel, instead of or in addition to using a keyboard, for example.
It is desirable to prevent dust from getting into the space between the touch panel 40 and the display unit 50. Dust could deteriorate image quality, and potentially damage the display unit 50 and/or touch panel 40. To prevent dust penetration, a flexible sealant R, such as adhesive tape, sponge or rubber, is disposed between the bezel 20 and a flat surface 101 of the plastic frame 10. The sealant R extends under the bezel 20, from the frame 10 to the display unit 50. During assembly, the flexible sealant R is compressed and deformed by the plastic frame 10 and the bezel 20 to form the seal to prevent dust from outside entering the space between the display unit 50 and the touch panel 40, through the space between the bezel 20 and the rear shield. 30. When double sided adhesive tape is used as the sealant R, the tape makes it harder to disassemble the parts of the display module for servicing, and could result in breakage of the panel 40 when the bezel is being removed. When non-adhesive type of sealant R is used (e.g., sponge or rubber), it allows for relatively easy disassembly and reassembly of parts, but requires a good fit between the frame 10 and the bezel 20, in order to form a good seal with the sealant R therebetween and along bezel and plastic frame. However, a good fit requires increased interference between parts, which requires higher tolerance. It has been challenging to maintain the required tolerance between and along the frame 10 and the bezel 20 consistently, given that the bezel is a stamped thin metal frame which inherently has local bendings and distortions along the longitudinal sections of the thin bezel, thus resulting in variations in the seal gap along and between longitudinal sections of the bezel and the plastic frame. Such variations in seal gap could result in sufficient opening around the sealant to allow dust to penetrate into the space between the display unit 50 and the touch panel 40.
What is needed is a structure that provides an improved dust seal.